THE BEGINNING OF THE TRIASSIC
Roughly 248 million years ago (mya), the Permo-Triassic extinction occurred. This is the largest extinction known. About 95% of all species and about 60% of the genera died out, including many marine animals (like the trilobite). The cause of the Permian extinction might have been global cooling, volcanic eruptions, or a decrease in the continental shelf area during the formation of Pangaea. This catastrophic extinction and continental rearrangement opened the way for the rise of the dinosaurs and mammals.

There were no dinosaurs at the beginning of the Triassic, but there were many amphibians and some reptiles and dicynodonts (like Lystrosaurus). During the early Triassic, corals appeared and ammonites recovered from the Permian extinction. Seed plants dominated the land; in the Northern hemisphere, conifers flourish. Glossopteris was the dominant southern hemisphere tree during the Early Triassic period.

OTHER ANIMALS AND PLANTS IN THE TRIASSIC

Glossopteris, a tree-like plant from the Permian through the Triassic Period. It had tongue-shaped leaves and was about 12 ft (3.7 m) tall. Glossopteris was the dominant plant of Gondwana (the southern continent).

During the late Triassic, 220 million years ago, the first true mammals appeared , like Eozostrodon. Some scientists believe that mammals evolved from a group of extinct mammal-like reptiles, Theriodontia, which were Therapsids. These primitive mammals were tiny and are thought to have been nocturnal. The earliest-known turtle, Proganochelys, appeared during the late Triassic.

Turtles , frogs , salamanders, lizards (including sphenodonts & snakes), and pterosaurs first appeared in the Triassic. Also in the Triassic was Pseudosuchia, possible ancestor of Archaeopteryx. Aetosaurs like Desmatosuchus lived during the late Triassic period. Insects began to undergo complete metamorphosis from larva through pupa to adult.

Leptocycas was a cycad, a primitive seed plant from the late Triassic period. It was a palm-like tree with a long, woody trunk and tough leaves. It lived in warm climates. This tree was about 4.8 ft (1.5 m) tall.

Seed ferns like Glossopteris, ferns and early species of gymnosperms (seed plants, such as the evergreens, in which the seeds are not enclosed) dominate the Triassic terrain. Cycads, with tufts of tough, palm-like leaves and a woody trunk, appeared in the late Carboniferous and were abundant in the Triassic. Laurasia was dominated by conifers, other seed plants and ferns; Gondwanaland was dominated by Dicroidium.

GEOLOGY AND CLIMATE DURING THE TRIASSIC
The Triassic's climate was generally hot and dry, with strong seasonality. The formation of the supercontinent of Pangaea at the beginning of the Triassic, 220 million years ago, decreased the amount of shoreline, formed mountains, and gave the interior of the supercontinent a dry, desert-like terrain. The polar regions were moist and temperate.
THE END OF THE TRIASSIC - AN EXTINCTION
The Triassic period ended with a mass extinction accompanied by huge volcanic eruptions about 208-213 million years ago. The supercontinent Pangaea began to break apart. 35% of all animal families die out, including virtually all labyrinthodont amphibians, conodonts, and all
marine reptiles except ichthyosaurs. Most synapsids, which had dominated the Permian and early Triassic, went extinct (except for the mammals). Most of the early, primitive dinosaurs also went extinct, but other, more adaptive dinosaurs evolved in the Jurassic.

No one is certain what caused this late Triassic extinction; possibilities include global cooling or an asteroid impact. A 210 million-year-old meteor cratersurrounding Manicouagan Reservoir, Quebec, Canada, may be the remains of the culprit.

This extinction allowed the dinosaurs to expand into many niches that were now unoccupied. Dinosaurs would become increasingly dominant, abundant and diverse, and remained that way for the next 150 million years.

THE NAME TRIASSIC
The Triassic period was named in 1834 by the German geologist Friedrich August Von Alberti (1795-1878) (it was originally named the "Trias"). It got its name because this period of geologic time is represented by a three-part division of rock types in Germany. These three distinctive rock layers are (from the bottom or earliest) the Bunter (which is brown sandstone and red beds), the Muschelkalk, and the Keuper. These are local rock types that are not found globally.